Bit Error Rate Characteristics Research Articles

Application of the method of equivalent message encoding structures to simplify coding complexity

Formulation of the problem. Modern telecommunication technologies make it possible to transmit data over long distances with limitations in the form of low power consumption and low error rate using error correction codes. The use of such codes plays an important role and is necessary to detect and correct errors caused by signal distortion and noise in the communication channel. According to Shannon's channel coding theorem, the probability of error can be arbitrarily small or close to zero if the encoding rate of transmission R is less than or equal to the bandwidth of channel C. Assuming that the bandwidth C is achievable, we can calculate the minimum signal-to-noise power ratio (SNR) to achieve zero error, or an arbitrarily small error called the Shannon limit, while maintaining R ≤ C. This article discusses a method of applying equivalent message encoding structures to construct low-density parity-checking (LDPC) codes. Low-density parity-checking (LDPC) codes are a class of linear block codes in which the complexity of iterative decoding increases linearly with increasing block length. Standard LDPC codes without modifications are considered to demonstrate the effectiveness of the proposed method, which is expected to provide high encoding speed when transmitting messages with a short block length. The method of obtaining equivalent structures allows: to reduce the computational complexity of encoding and decoding; to provide the possibility of finding a new encoding scheme and evaluating its effectiveness. The validity of the method for obtaining equivalent message encoding structures is evaluated by modeling the bit error rate (BER) of LDPC codes. Purpose. to show the effectiveness of the use of equivalent structures for various methods of compression of transmitted information, to minimize the complexity of encoding, while maintaining energy efficiency, correcting ability and data transfer rate. Results. A method is considered for obtaining equivalent message element encoding structures that can be used to create more LDPC codes for data transmission applications with a short block length. The cascade principle of constructing an equivalent generator and a parity check matrix was analyzed, which also leads to minimizing the computational complexity of the encoder and decoder. An equivalent structure G can be obtained from cascading two (or more) matrices by modifying the second matrix so that it has a unit matrix with the size of the parity check length and a shift to the right by k bits. On the other hand, the equivalent structure H can be obtained by simply cascading directly the second matrix and shifting to the right by k bits. According to the simulation results, the proposed method is adequate, since LDPC codes have the same BER characteristics as codes based on the low density generator matrix (LDGM). During the simulation, it was concluded that the SPC codes (single parity check (single parity check (SPC)) are the most efficient codes (for a given block length), since SPC codes have the smallest interval up to the Shannon limit. Practical significance. The results presented in this article will give a new insight into the development of simple channel coding of LDPC codes of short block length with high encoding speed for future applications with lower power consumption.

HP-DF SSK Method for UAVs Communication in Cooperative Multi-Hop Rician Networks

This paper presents techniques that are expected to improve the bit error rate (BER) performance of Unmanned Aerial Vehicles (UAVs) communication systems. The decode-and-forward (DF)-based cooperative multi-hop Rician network using space shift keying (SSK) modulation is employed for this purpose. The SSK modulation and cooperative communication are merged and used together. This enhances the BER performance for multiple-input multiple-output (MIMO) channels, thus accentuating its significance as an important technique for consistently reliable communication methodology while, at the same time, eliminating wastage of energy. The new technique is named as high performance (HP) due to not only BER performance improvement but also increase of the diversity of the communication system. This new model is further used for multi-hop networks and the resulting BER characteristics are assessed for possible enhanced performance in Rician channels. The paper also showcases the generalized-n-hop BER equation for various multi-hop DF-based cooperative communication systems in diverse UAV models. The Monte Carlo simulations further confirm the theoretical results that already exist for transmit-receive antennas. This work also underlines the fact that the number of hops in a communication system has no bearing whatsoever on the BER performance diversity value.

Power Optimization of Three Dimensional Turbo Code Using a Novel Modified Symbiotic Organism Search (MSOS) Algorithm

In modern communication system error-control coding scheme is used to elevate the immunity of noisy communication channel. Turbo code (TC) is considered as one of the significant channel coding schemes which approaches to the Shannon limit. An upgraded version of TC named as 3 dimensional turbo code (3D-TC) has been emerged as a challenging research area in recent past. Meanwhile, considerable improvement in bit error rate (BER) performance of the TC has been achieved by incorporating suitable optimization algorithms. Motivated by above research trends, a modified symbiotic organisms search (MSOS) algorithm has been proposed by changing the organism structure and selection criteria of a newly developed symbiotic organisms search (SOS) algorithm. Subsequently the proposed MSOS has been used to design an improved 3D-TC. Here an optimal power allocation scheme of a new class of 3 dimensional turbo encoder has been investigated to improve its BER characteristics mainly in high SNR regions. Furthermore, the BER performance of the proposed 3D-TC code has been compared with conventional 2D serially concatenated and parallel concatenated turbo code as well as conventional 3D-TC. Finally, the BER performance of the proposed MSOS optimized 3D-TC has been compared with the SOS optimized 3D-TC and harmony search optimized 3D-TC.

Polybinary Shaping for Highly-Spectral-Efficient Super-Nyquist WDM QAM Signals

In Super-Nyquist wavelength-division multiplexed (WDM) systems, in which WDM channel spacing is smaller than a signal baudrate, there is a tradeoff relationship between the WDM crosstalk and inter-symbol interference due to the tight spectral shaping. For optimizing the tradeoff relationship, polybinary shaping with maximum likelihood sequence estimation is introduced. In this paper, we numerically and experimentally investigate the bit-error rate characteristics of the Super-Nyquist WDM quadrature amplitude modulated signals with polybinary shaping in order to clarify the relationship between the spectral efficiency and required signal-to-noise ratio (SNR). These results indicate that the Super-Nyquist WDM technique based on polybinary shaping is effective to optimize the spectral efficiency for the target required SNR equivalent to the target transmission distance.

PAPR reduction technique by inserting a power-concentrated subcarrier for CO-OFDM

Optical orthogonal frequency division multiplexing (OFDM) signals suffer from the nonlinear effects of an electric-to-optical modulator and fiber due to high peak to average power ratio (PAPR) characteristics. We propose a power-concentrated subcarrier method for use in OFDM systems to reduce PAPR of the OFDM signal without increasing system complexity or side information. The PAPR can be reduced by simply inserting a power-concentrated subcarrier (PCS) to replace the zero in the end of the signal spectrum at the zero padding stage. The simulation is performed with a conventional CO-OFDM transmission system with a PCS under dispersion and a nonlinear effective fiber to estimate PAPR using complementary cumulative distribution function (CCDF), error vector magnitude (EVM), and bit-error-rate (BER) characteristics. After a 2000-km transmission, the conventional CO-OFDM had an optimal fiber launch power of −6dBm from the BER characteristics. In contrast, the proposed CO-OFDM with a PCS improves transmission performance in terms of log(BER) as much as −0.67 by an increased fiber launch power of −1dBm with 60% concentrated-power of the PCS.

MIMO-MMSE Model using Multiple Active Antennas for Rayleigh Fading Channel

Spatial Modulation (SM) is a technique that can enhance the capacity of MIMO schemes by exploiting the index of transmit antenna to convey information bits. This paper describes a MIMO transmission scheme that combines SM and spatial multiplexing. In the basic form of SM, only one out of NT available antennas is selected for transmission in any given symbol interval. This paper proposes to use more than one active antenna to transmit several symbols simultaneously. This would increase the spectral efficiency and decreases BER (bit error rate) at the receiver, an MMSE detector is employed to jointly estimate the Transmitted symbols as well as the index of the active transmit antennas. The results show that the detection based on zero forcing is good for noise free channel and is successful in removing ISI, but MMSE is a better choice than ZF in terms of BER characteristics and under Noise performance. In MIMO transmission scheme the uncorrelated fading channel also called statistical model is used for the effect of a propagation environment on a radio signal. Sometimes use of multiple antenna techniques is problem depended but it used because it gives better performance like heavily built urban environment where radio signals are fade and scattered.

Multi-level signaling in the Stokes space and its application to large-capacity optical communications

The Stokes vector of an optical signal does not depend on its absolute phase; therefore, we can construct the phase-insensitive optical communication system, using the Stokes vector as a modulation parameter. In such a system, multi-level optical signals can effectively be designed in the three-dimensional Stokes space and demodulated either by direct detection or by coherent detection, where low-complexity digital-signal processing (DSP) is employed. Although this system has the disadvantage that adaptive equalizers can hardly be implemented in the digital domain, it is still an attractive solution to large-capacity (≥ 100 Gbit/s) and medium-or short-reach (≤ 100 km) transmission. In this paper, we discuss the receiver configuration for the multi-level signal in the Stokes space and the efficient DSP algorithm for demodulating such a signal. Simulation results demonstrate that 2-, 4-, 8-, 16-, and 32-ary signals in the Stokes space have good bit-error rate (BER) characteristics. Especially, the 16-ary signal at the moderate symbol rate of 25 Gsymbol/s can reach the bit rate of 100 Gbit/s even by using direct detection.

All-optical polarization-insensitive non-return-to-zero-to-pulsewidth tunable return-to-zero conversion

We demonstrate polarization-insensitive non-return-to-zero (NRZ)-to-pulsewidth tunable return-to-zero (RZ) conversion based on a Raman amplifier (RA)-based pulse compressor and a fiber-based NRZ-to-RZ converter, which consists of a polarization diversity loop. We measure the bit-error rate (BER) characteristics of the input NRZ signal and the converted RZ signals. The power penalty of less than 0.2 dB between the converted RZ signals with different power ratios proved the polarization insensitivity. Moreover, by changing the Raman pump power of the RA-based pulse compressor, the pulsewidths of the converted RZ signals were flexibly tuned from 10 to 2 ps, which proved NRZto-RZ conversion with pulsewidth tunability. In all cases, clear eye diagrams were obtained.

Analysis of an offset modulation transmission

In this article, a method called offset modulation (OM-OFDM) is proposed to control the peak-to-average power ratio (PAPR) of an orthogonal frequency division multiplexing (OFDM) signal. The theoretical bandwidth occupancy of the proposed offset modulated signal is derived. Using these bandwidth occupancy results, a closed-form theoretical bit error rate (BER) expression for an offset modulated transmission is derived and validated. Thereafter, a BER comparison between OM-OFDM and OFDM at a PAPR value of 13 dB shows that both methods offer similar BER characteristics for frequency selective fading channel conditions. The OM-OFDM method in addition is able to accurately control the PAPR of a transmission for a targeted BER. The authors have further proposed a newly applied power performance decision metric, which can be used throughout the PAPR field, in order to compare various methods. By using this power performance decision metric, the authors show that OM-OFDM offers between 4 dB–1.2 dB (60.34%–24.6%) and 4.1 dB–1.2 dB (60.8%–23.6%), net power performance gain (at a BER of 10−4) when compared to a clipped OFDM, OFDM, tone reserved (TR) OFDM and an active constellation extended (ACE) OFDM transmission in a frequency selective fading channel. Finally, by using a complementary cumulative distribution function (CCDF), the OM-OFDM method is shown to offer between 3.2 dB and 2 dB PAPR reduction (at a CCDF of 10−1) when compared to an OFDM, TR, clipped, and ACE OFDM transmission.

Impact of Transmission Impairments on Demultiplexed Channels in WDMPONs Employing AWG-Based Remote Nodes

This paper deals with the performance evaluation of a passive optical network (PON) using wavelength division multiplexing (WDM) by employing an arrayed-waveguide grating (AWG) in the remote node (RN). In such WDM-based PONs (WDMPONs) the RN demultiplexes the downstream WDM signal via distinct output ports through a static wavelength-routing mechanism. An analytical model is developed for evaluating the bit error rate (BER) performance of the demultiplexed channels as a function of the output port location in the AWG by incorporating a novel spectral-to-spatial domain transformation technique. The proposed model captures the impact of finite laser linewidth as well as the AWG characteristics in determining the received signal power at the individual optical network unit (ONU) attached to the output port (due to spectral-to-spatial mapping). Furthermore, the BER model accounts for several transmission impairments, including beat noise due to interchannel crosstalk in the AWG. Results indicate that the signal power captured by the output ports of AWGs and hence their BER values are not only determined by the Gaussian focal-field pattern of the AWG but also by the power spillover from adjacent ports for broader linewidths and higher data rates. A significant interplay is observed between data rate, source linewidth, and relevant device parameters while examining the loss and BER characteristics of a given AWG-based WDMPON.

이중 선택적 채널 OFDM 시스템을 위한 블록 선형 MMSE 등화 방식의 성능 분석

본 논문에서는 이중 선택적 채널 OFDM 시스템을 위한 블록 선형 MMSE(Minimum Mean Square Error) 등화 방식의 성능을 컴퓨터 모의실험을 통하여 분석한다. 블록 선형 MMSE 등화 방식의 BER(Bit Error Rate) 성능은 SNR(Signal-to-Noise Ratio)이 증가함에 따라 BER이 처음에는 감소하다가 SNR이 일정 값을 넘어서면 BER이 오히려 증가하는 다소 특이한 현상을 나타낸다. 본 논문에서는 블록 선형 MMSE 등화 과정에 포함된 선형연립방정식 계수 행렬의 상태수(condition number) 분석을 통하여 이러한 블록 선형 MMSE 등화 방식의 BER 특성을 규명하고 높은 SNR 값에서의 BER 성능 저하를 개선하는 새로운 방안을 제시한다. In this paper, we analyze the performance of the block linear MMSE equalization for OFDM systems in doubly selective channels by computer simulations. The block linear MMSE equalization shows somewhat unusual BER characteristics in that the BER curve drops at first as SNR increases but then rises up as SNR increases further beyond some point. In this paper, we investigate the BER characteristics of the block linear MMSE equalization by analyzing the condition number of the coefficient matrix in the linear system involved in the equalization process, and propose a new method to avoid the BER performance degradation at high SNR.

BER and SFDR Characteristics of an FWM-Based All-Optical Frequency Upconverter

We have experimentally investigated the bit-error-rate (BER) and spurious-free dynamic range (SFDR) characteristics of an all-optical frequency upconverter based on the four-wave-mixing effect in a semiconductor optical amplifier for radio-over-fiber networks. The generation and error-free transmission of an optical radio-frequency signal having 155.52-Mb/s differential phase-shift keying data at a carrier frequency of 26.5 GHz are achieved. The dynamic ranges of an optical intermediate frequency (IF) input signal estimated from the BER and SFDR measurements are approximately 12 and 16 dB, respectively. The SFDR of the upconverter is larger than 77 dBmiddotHz2/3 for the IF frequencies ranging from 1 to 12 GHz.

Linewidth-tolerant 10-Gbit/s 16-QAM transmission using a pilot-carrier based phase-noise cancelling technique

We experimentally demonstrated linewidth-tolerant 10-Gbit/s (2.5-Gsymbol/s) 16-quadrature amplitude modulation (QAM) by using a distributed-feedback laser diode (DFB-LD) with a linewidth of 30 MHz. Error-free operation, a bit-error rate (BER) of <10(-9) was achieved in transmission over 120 km of standard single mode fiber (SSMF) without any dispersion compensation. The phase-noise canceling capability provided by a pilot-carrier and standard electronic pre-equalization to suppress inter-symbol interference (ISI) gave clear 16-QAM constellations and floor-less BER characteristics. We evaluated the BER characteristics by real-time measurement of six (three different thresholds for each I- and Q-component) symbol error rates (SERs) with simultaneous constellation observation.

On the Transceiver Types of IR-UWB Systems at Sub-Nyquist Sampling Rates

In this paper, we present a unified performance analysis for different impulse radio (IR) ultra-wideband (UWB) transceiver types employing various modulation options and operating at sub-Nyquist sampling rates. Stored reference (SR), transmitted reference (TR), and energy detector (ED) receivers are considered employing one of the binary phase shift keying (BPSK), pulse position modulation (PPM), and on-off keying (OOK) modulation types. Realistic UWB channel models (the IEEE 802.15.4a channels) and practical pulse shapes (the root-raised cosine pulse) are used to characterize the statistics of the captured energies of different transceiver types at low sampling rates. The bit error rate (BER) expressions for different transceiver/modulation types are provided explicitly in additive white Gaussian noise channels. In multipath channels, the BER expressions are conditioned on the captured energies; then, the captured energy histograms at sub-Nyquist rates are used towards a semi-analytic evaluation of the BER for different transceiver/modulation combinations. The analyses are then verified via simulations using IEEE 802.15.4a channel models. The results show that in addition to their lower implementation complexities, the TR and ED receivers may be more favorable compared to SR receivers at low sampling rates in terms of their BER characteristics as well.

Transmission characteristics of wireless baseband transmission under multipath environments using real‐valued signal analysis

AbstractDiscussed here are real‐valued signal analysis and wireless baseband transmission, a system for transmitting baseband signals directly from an antenna, and transmission characteristics under a multipath environment. The field of wireless transmission generally handles band signals in which information rides on a carrier wave, and therefore signal analysis is not the direct analysis of real high‐frequency signals (real‐valued signals) and is performed with a system expressed using complex numbers, called an equivalent baseband system. However, wireless baseband transmission is based on a transmission system which does not use carrier waves and cannot be handled with an equivalent baseband system. Consequently, it is necessary to have a system of real‐valued signal analysis for handling baseband signals, which are real‐valued signals, without additional processing. The BER (bit error rate) was used as the standard for evaluating transmission characteristics under a multipath environment of wireless baseband transmission using measured channel characteristics with that algorithm. With a computer, the BER characteristics were found by varying the reflection coefficient, number of delay symbols, the ratio of direct wave power and reflected wave power, and the number of reflected waves. As a result, it was clear that the dominant factor in a multipath environment is the ratio of direct wave power and reflected wave power. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 90(10): 9–22, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20347

Performance analysis of content-addressable search and bit-error rate characteristics of a defocused volume holographic data storage system

One of the methods for smoothing the high intensity dc peak in the Fourier spectrum for reducing the reconstruction error in a Fourier transform volume holographic data storage system is to record holograms some distance away from or in front of the Fourier plane. We present the results of our investigation on the performance of such a defocused holographic data storage system in terms of bit-error rate and content search capability. We have evaluated the relevant recording geometry through numerical simulation, by obtaining the intensity distribution at the output detector plane. This has been done by studying the bit-error rate and the content search capability as a function of the aperture size and position of the recording material away from the Fourier plane.

Modeling and verification of FEC performance for optical transmission systems using a proposed uniformly quantized symbol error probability model

We investigate the estimation of the bit-error rate (BER) performance of optical transmission systems with forward error correction (FEC) coding using a proposed uniformly quantized symbol error probability model. This model has been verified by the measurement of BER characteristics of coded and uncoded 10 Gb/s optical signals transmitted over 100 km. The measured results are very similar to the calculated results from the proposed model as well as Monte Carlo (MC) simulations. Our results suggest that the proposed uniformly quantized symbol error probability model using more than 8-decision levels can be applied to estimate BER performance for coded systems without degrading accuracy.

An Automated Method for BER Characteristics Measurement

Traditionally, the bit error rate (BER) characteristics were measured for a certain number of bit-energy-to-noise ratio ( Eb/No). For each point, a sample of r bits is used, which depends on the expected BER value. The smaller BER value, the bigger the sample r. Thus, to obtain the same accuracy at each point, a method of trial and error should be used. Therefore, this method extends the time of measurement and measures BER values at all points with different accuracy. This paper presents a method which allows the automated and accurate measurement of the BER characteristics at a number of points with equal accuracy at each point by using the minimum sample size r. The method is tested by measuring BER characteristics of an FFSK modem.

Current mode, low-power, on-chip signaling in deep-submicron CMOS technology

This paper reports an analogy between on-chip signaling and digital communication over a band-limited channel. This analogy has been used to design a scheme for low-power, on-chip signaling, robustly resistant to power-supply noise. The technique uses multilevel, current-mode signaling as its core. The number of levels is determined by estimating the bandwidth of the wire. A closed-form expression has been presented here describing the bandwidth of a wire modeled as a first-order RLC circuit. An algorithm is presented for computing the levels of the current given target bit rate, bit-error rate, and wire characteristics. Simulation results using HSPICE from Avant! show that the algorithm for computing the wire bandwidth presented here has an average error of less than 10%. Experimental results on a set of benchmark signaling problems implemented in a 0.25-/spl mu/m 2.5-V CMOS process, show that using four levels of current instead of the standard two levels allows a two-fold reduction in the power and a reduction of 1.4 times the area.

LDPC codes based on mutually orthogonal latin rectangles and their application in perpendicular magnetic recording

We present a large family of low-density parity-check (LDPC) codes constructed from mutually orthogonal Latin rectangles. The construction is conceptually simple and gives high-rate LDPC codes with a structure of the parity check matrix that leads to a low complexity implementation of encoders and decoders. The bit-error rate characteristics are characterized by simulations of the soft iterative decoding in perpendicular magnetic read channels with different partial-response targets and types of noise.